talk about a browser hijack
that sucks....
i'd run some malware software and look for it
open your control panel and click on internet so that's already open
then minus it to your taskbar
then right click your S-B icon and run it as administrator
once there... @ s-b see if your re-directed
and if so pop the internet settings back up off your taskbar
and see if it says sittercity.com in there
then high- light it and delete it...

put what ever your homepage is supposed to be in that box and hit apply then save